There a variety of techniques which have been employed to process the dross generated when melting metal in foundries. These dross processing systems are designed to separate metal from the dross, which is a mixture of metal, oxides, and other inclusions. Many of these techniques were developed to treat the dross at a site remote from the furnace. The systems have been designed to process large volumes of dross and have employed large and complex machinery, including mixing and pressing equipment to process the dross. Typical examples of such systems are disclosed in U.S. Pat. Nos. 3,198,505; 4,386,956; and 4,938,457.
In these systems, the metal which is present in the dross is separated by various techniques, depending on the system. In some instances, the metal is separated by pressing the liquid metal out of the oxide in which it was entrapped, while in other systems the metal is recovered by mechanically stirring the dross to promote coalescence of the metal, or by spinning the mixture to separate the metal by centrifugal force. Fluxes are also frequently employed to enhance the coalescence of the metal dispersed in the dross.
Simpler systems which depend solely on gravity for separation of the metal from the oxides have been developed, with metal holding pots which have a large thermal mass to assure that high temperatures can be maintained to maintain the entrapped metal in a molten state (see, for example, U.S. Pat. No. 862,008). These systems frequently employ metal vessels which have a large thermal mass and, when preheated, provide a soaking vessel which allows sufficient time for the metal entrapped in the dross to percolate therethrough. These vessels are generally massive, difficult to transport to the furnace conveniently, or present difficulty in removing the material contained therein.
Thus, there is a need for a simple portable self-contained system which can effectively reclaim the entrapped metal in the dross formed during melting of metals.